Tens of thousands of kids in Arizona got a free breakfast this week from McDonald's. Franchise owners in a handful of states have gotten together to give out food on the days that schools administer big standardized tests.

The promotion was such a big draw at a Central Phoenix McDonald's Tuesday morning that it took some effort to squeeze through the front door. "I suspect that we'll serve over 500 students this morning, just in this restaurant alone," says franchise operator Jerry Gehrke.

Last year, Arizona McDonald's restaurants gave out more than 81,000 meals to kids on test day. Restaurants in a handful of other states, including Florida, Oklahoma and Minnesota, have also participated. Gehrke spends $2 a head on each student's Egg McMuffin, a pack of apple slices, and a carton of milk or orange juice. He says it's good for the kids, who need brain food to ace the state's standardized tests.

The free breakfast also builds customer loyalty.

"It does. It makes me feel like, oh my God, after so much money being spent here, I finally get something back," says mom Naomi Quintero, who eats at the restaurant every weekend with her family.

Quintero's sons will each get 18 grams of protein in their egg sandwich. That's pretty good fuel for a test, said Simin Levinson, a nutritionist at Arizona State University. "I would consider it to be a well-rounded meal," she says.

But it's not the only place to get one. The nearby Creighton School District says about 4,700 students eat a free breakfast every day. Their families are poor enough to qualify for subsidized meals. Levinson says these meals are nutritionally similar to the free McDonald's menu. But if she had a choice, she'd take the one that's free of corporate influence.

"This is where I can't help but be a little bit skeptical: Is this a ploy that McDonald's is using in creating a whole new generation of consumers that will be brand loyal specific to McDonald's?" she says.

That worries Levinson because she says the next time those 500 kids are in line, they're likely to chose something loaded with fat and sodium.